Rubidium compounds: rubidium fluoride

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The rubidium in rubidium fluoride formally is in the oxidation state 1.

Crystal structure of rubidium fluoride

Rubidium fluoride

  • Formula as often written: RbF
  • Hill system formula: F1Rb1
  • CAS registry number: [13446-74-7]
  • Formula weight: 104.466
  • Class: fluoride

Synonyms

  • rubidium fluoride
  • rubidium(I) fluoride

Physical properties

  • Colour: white
  • Appearance: crystalline solid
  • Melting point: 795°C; 833°C
  • Boiling point: 1410°C
  • Density: 3200 kg m-3

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Element analysis

Element percentages for the elements in rubidium fluoride
Element %
F 18.19
Rb 81.81

Synthesis

One way to make rubidium fluoride is to react the hydroxide with hydrofluoric acid. The resulting salt can then be purified by recrystallization.

RbOH(aq) + HF(aq) → RbF(aq) + H2O(l)

Rubidium(I) fluoride can also be made by the neutralization of rubidium(I) carbonate with hydrofluoric acid (in a platinum vessel since HF reacts with glass). The resulting salt can then be purified by recrystallization.

Rb2(CO3)(aq) + 2HF(aq) → 2RbF(aq) + H2O(l) + CO2(g)

While not a normal route of preparation because of the expense, rubidium metal reacts vigorously with all the halogens to form rubidium halides. So, it burns with fluorine, F2, to form rubidium(I) fluoride, RbF.

2Rb(s) + F2(g) → 2RbF(s)

Solid state structure

  • Geometry of rubidium: 6 coordinate: octahedral
  • Prototypical structure: NaCl (rock salt)

Crystal structure of rubidium fluoride

Isotope pattern

What follows is the calculated isotope pattern for the RbF unit with the most intense ion set to 100%.

Formula: Rb1F1

mass  %
104 100.0 __________________________________________________
105 0.0
106 38.6 ___________________

References

The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

  • R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
  • N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
  • A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
  • R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
  • A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
  • A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
  • J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
  • D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
  • J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
  • J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.

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rubidium atomic number